Circuit interrupter



Jan. 14, 1936.. H. J. CRABBS I CIRCUIT INTERRUPTER 2 Sheets-Sheet 1 Fi'led Nov. 11, I933 ATTORN WITNESISES: I -LM Jan. 14, 1936.

H, J. CRABBS CIRCUIT INTERRUPTER Filed Nov. 11, 1953 2 Sheets-Sheet 2 4 25 INVENTOR WITNESSES:

Patented Jan. 14, 1936 oFFlcs CIRCUIT llN'lllElRRlUP'lllER lllerbert .ll. Crabbs, Wilkinsburg, Pa, assignor to Westinghouse Electric & Manufacturing Company, East llittsburgh, Pa, a corporation of Pennsylvania Application November 11, 1933, sci-in No. 697,611

14 Claims.

My invention relates to circuit interrupters and particularly to manually operated disconnecting switches for use with medium and high voltage transmission circuits.

Switches of this type comprise a pair of spaced insulators, a contact mounted on each of the insulators, a blade for bridging the insulators, and a means for actuating the blade. It is desirable that the plane of movement of the blade be parallel to the axis of the insulators, this construction yielding a vertical break switch which occupies a minimum of ground space. It is also desirable that the insulator columns be subjected to as little cantilever stress as is possible, since all of the economically practical insulators, while capable of resisting large torsional stress, fail when subjected to relatively low cantilever stress.

These switches are ordinarily used for disconnecting or sectionalizing portions of a transmission line. Usually they are mounted outdoors and are subjected to very severe weather conditions as a result of ice and sleet formations. Moreover, in the normal course of events, the switches are operated very infrequently, thus providing an almost ideal condition for oxide and corrosion formation. The switches must be low in cost, due to the large number used; they must be capable of reliable operation under the most adverse conditions without unduly straining the supporting insulators; the contact mechanism must include means for cutting through corrosion during the circuit closing operation, so as to ensure good electrical contact; and further, the switches must be inherently safe in order to prevent injury to the operator or to the protected equipment.

It is an object of my invention, therefore, to provide an improved high voltage disconnecting switch that shall beinexpensive to manufacture, safe and reliable in operation, and that shall include means for securing highpressure contact between the engaging contact surfaces without unduly straining the supporting insulators.

A further object of my invention is to provide a simple and efiective means for causing awiping action between the engaging contact surfaces of a disconnecting switch.

A further object of my invention is to provide means for positively locking the movable blade of a disconnecting switch in the closed circuit position, the locking means to be releasable by actuation of the blade operating mechanism.

Another object of my invention is to provide a disconnecting switch wherein the blade means and the cooperating contact means shallbe rigidly mounted so as to preserve the spacing of the supporting insulators and thus increase the reliability of operation of the device.

A further object of my invention is to provide a disconnecting switch having a pair of supporting insulators, a blade for bridging two insulators, and means supported externally of the two supporting insulators for actuating the blade.

A still further object of my invention is to provide an improved three insulator disconnecting switch which shall accomplish the above stated objects through the use of a single actuating mechanism operable through the rotation of one of the three insulators.

These and other objects of my invention will be more clearly understood from the following description of an embodiment of my invention, as applied to a three insulator vertical break disconnecting switch.

Referring to the drawings, Figure 1 is an elevational view, partly in section, showing a three insulator vertical break disconnecting switch embodying the principal features of my invention. The switch is in the closed circuit position.

Fig. 2 is a fragmentary elevational view showing the disconnecting switch illustrated in Fig. 1v in the partially open position,

Fig. 3 is a plan view of the disconnecting switch shown in Fig. 1 in the closed circuit position Fig. 4 is an elevational view of the disconnecting switch shown in Fig. 1 in the open circuit position,

Fig. 5 is a fragmentary plan view of the contact structure of the switch illustrated in Figs. 1 to 4 in the partially open position,

Fig. 6 is a fragmentary elevational view showing the contact structure of the switch illustrated in Figs. 1 to 4 in the fully closed position,

Fig. '7 is..a sectional viewv taken on the line VII-VII of Fig. 6 and Figs. 8 to 11, inclusive, are fragmentary detail views showing modified forms of contact structure suitable for use with the disconnecting switch shown in Figs. 1 to 4.

As shown in the drawings, the preferred embodiment of my invention includes a base or support member I for the switch, a pair of insulators 3 and 5 rigidly mounted on the support member I through the agency of bolts 1, a contact jaw 9 mounted on the upper insulator 3, a pair of blade members II and I3 pivotally supported on the lower insulator 5, a rotatable insulator l5 likewise mounted on the base memher I, and actuating means ll whereby the blade members are moved into and out of engagement with the contact jaw 9 through the rotation of the rotatable insulator I5.

The two stationary insulators 3 and 5 and the rotatable insulator I5 are of the usual high voltage type and comprise a number of ceramic rain shields cemented together with a cap I9 at the upper end and a supporting member at the lower end. The supporting member 2| of the two stationary insulators 3 and 5 terminates in a flange 23 which is affixed to the base I by the bolts I. The contact jaw 9 which is shown in detail in Figs. 6 and 7 is cast integral with the cap member I9 of the upper stationary insulator 3 and comprises a rigid jaw portion 25 having an opening 21 therein for engaging the contact portion of each of the movable blade members II and I3. The opening 21 is restricted by means of two boss portions 29 which project inwardly from the opposed sides of the rigid jaw. These boss portins 29, as will be explained later, serve to lock the blade members I I and I3 in position when the switch is completely closed.

A bifurcated supporting frame 3| having two opposed side portions 33 is cast integrally with the cap I9 of the lower insulator 5. These side portions 33 are provided with aligned openings which serve to support the shaft 35 upon which the assemblage of the blade members II and I3 rotates.

The rotatable insulator I is supported on the base member I through a ball bearing 31 and a collar 39 which are both keyed to the operating shaft 4|, one end of which is cemented to the base portion of the insulator, thereby permitting the insulator to be rotated by suitable means (not shown) afilxed to the end of the operating shaft. The cap portion I9 of the rotatable insulator I5 comprises an upstanding crank member 43 which terminates in a spherical bearing portion 45. This portion, as will be explained later, cooperates with a'socket 49 aflixed to the end of the tie operating member 41 to move the blade members II and I3 to the open and to the closed circuit positions.

The two blade members II and I3 are pivotally supported on the shaft 35 through the agency of a bearing member 5| which is provided with a pair of radially projecting crank. members 53 and 55 formed integrally therewith. Each of the crank members 53 and 55 is provided with a threaded opening for engaging one of the stud bolts 51 which serve to pivotally join the ends of the two blade members II and I3 to the bearing member. Suitable machined surfaces (not shown) are provided on the end portions of the blade members II and I3 and on the cooperating portions of the crank members 53 and 55 to limit the friction therebetween.

The bearing member 5| is provided with a third crank member 59 which is formed integrally therewith and which projects radially therefrom in substantially the same direction as the blade supporting crank member 53. This crank member 59 terminates in a pivot pin 6| which provides a bearing surface for the link 63." This link 63 is pivotally joined to the jaw portion 55 of the tie member4'I, which is positioned intermediate the rotary insulator I5 and the assemblage of the two blade members II and I3, by means of two short pins 61. It will be noted that since the tie link 41 is operatively connected to the rotary insulator I5 through a ball and socket connecting means, and since it is connected to the assemblage of blade members by means of a universal joint connection, the rotary motion of the rotatable insulator I 5 is transmitted directly to the bearing member 5| in order to operate the switch.

The pivoted end of the blade member II is provided with a crooked portion 69 which, as will be explained later, permits the blade members to be locked in the closed circuit position. The blade members II and I3 are preferably constructed of copper rod or tubing and are thus possessed of considerable inherent resiliency. Each of the blade members terminates in a contact portion II which is welded or otherwise rigidly affixed to the end thereof. These contact portions II are joined together in the preferred embodiment of my invention by a linkage which comprises a pair of links I3 pivotally fastened at one end to each of the blade members by means of pivot pins I5. The links I3 are likewise resilient and may be constructed with a slightly bowed portion 11, as is shown particularly in Fig. 6, in order to improve the operation of the switch.

The cap members I9 for the two stationary insulators 3 and 5 are provided with a terminal portion -I9 for connecting the switch in an electrical circuit. The two blade members II and I3 are electrically connected to the cap portion I9 of the lower insulator 5 by means of two flexible shunts 8| which are brazed or welded to the blade members at one end and are similarly fastened to the cap member itself at the other end. These shunts 8| assure a good electrical connection from the terminal portion I9 of the lower insulator to the blade members, irrespective of the pivoted support for each of the blades and add much to the reliability of the operation of the switch.

The disconnecting switch is shown in the closed circuit position in Figs. 1 and 3. To open the circuit, the operating shaft 4| is rotated in a clockwise direction (Fig. 3). The first effect of this rotation is to move the center of the ball and socket joint which is formed by the spherical bearing 45 and the socket 49 from the position shown in Fig. 13 to a position to the left of the line connecting the axis of rotation of the rotatable insulator and the axis of rotation of the link 63 (i. e. the axis of the pin 6|); when in the position shown in Fig. 3, the switch is effectively locked in, due to the fact that the blade actuating means is at dead center and rotation of the rotatable insulator I5 in a counter-clockwise direction is prevented by suitable stop means not shown. Further clockwise rotation of the rotatable insulator I5 causes the bearing member 5| to move from the position shown in Figs. 1 and 3 to the position shown in Fig. 2, thereby causing the two blade members I I and I3 to move longitudinally in opposite directions with respect to each other in apath which is defined by the connecting links I3 and the crank members 53 and 55 which form a part of the bearing member 5|. The force of gravity biases the blade members II and I3 to the position shown in Fig. 2 throughout the circuit opening and circuit closing operations.

In addition to the longitudinal movement of the blades II and I3 which is produced by the initial rotation of the rotatable insulator I5, the blades are caused to move laterally toward each other due to the restraining action of the connectin links I3. Thus, during the circuit opening operation, the contact portions II of the blade members disengage the contact jaw 9 with a wiping ciently close together to permit the blade member to be moved through the restricted portion of the contact jaw. Additional rotation of the rotatable insulator will then move the switch to the position shown in Fig. 4 which is the normal open circuit position. When the switch is in this position, the rotatable insulator has been moved approximately 180, thus bringing the centers of the bearingpin 6|, the ball and socket joint. and the axis of the insulator |5 itself into substantial alignment, or what is more accurate to a dead center position. This arrangement serves to rigidly hold the switch in the open circuit position through the exertion of a very small latching force on the main operating shaft M.

The circuit closing operation is essentially the reverse of a circuit opening operation. The operating shaft 4| and with it the rotatable insulator l5 is rotated in a counter clockwise direction (Fig. 3). This movement is transmitted to the bearing member 5|by means of the tie link 37 and the crank member 59, and the two blade members H and I3 are moved from the position shown in Fig. 4 to the position shown in Fig. 2, the biasing action of the force of gravity assuring the proper positioning of the blades so that the contact portions 1| will move through the restricted portion of the contact jaw 9 without dlfficulty. Subsequent rotation of the rotatableinsulator IE will then cause the blade members i! and i3 to move longitudinally with respect to each other whereupon the contact portions 1| engage the cooperating portions of the jaw 9 with a wiping action. The movement of the connecting linkage from the position shown in Fig. 5 to the position shown in Fig. 3 acts very similar to a toggle in causing the cooperating contact portions of the blade members and the contact jaw to engage with a very high pressure contact. The amount of this contact pressure can be easily controlled through the substitution of different links 13 having more or less resiliency.

It will be noted that both the opening and the closing operations are carried out through the rotation of a single operating shaft 4| which actuates mechanism mounted entirely independently of the support means for the blademembers themselves. It will also be noted that substantially no cantilever stress is put on either of the supporting insulators 3 and 5 during the circuit opening or during the circuit closing operation, because the blades are moved at all times by forces which act in couples.

It will further be noted thatthe cooperating contact surfaces engage and disengage with a wiping action during the operation of the circuit interrupter. This effectively cuts through any corrosion or oxide formations which may exist and assures good electrical contact.

When the disconnecting switch is in the closed circuit position, as is shown particularly in Figs. 1 and 3, the bearing member 5| has been moved to a position where the blades H and I3 are effectively locked in place. That is, the pivot point of the shorter blade member l3 (the axis of the associated bolt 51) has been moved to a position beneath the line connecting the axis of the shaft 35 and the movableend of the blade l3 itself, and the pivot point of the longer blade member II (the axis of the other bolt 51) has been moved to a position above the line connecting the unpivoted end of that blade and the axis of the shaft 35. Thus, since the reaction forces of the contact jaw 9 urge the shorter blade member I3 in a direction of the rotatable insulator I5 and the longer blade member H in a direction away from the rotatable insulator l5, the bearing member 5|, due to the position of the pivot points of the blade members II and I3 is biased in a counter-clockwise direction (Fig. 1). This biasing reaction is taken up by the engagement of the crooked portion 69 of the blade member H with the body of the bearing member 5| itself and causes the reaction forces acting on the blade members to tend to hold the switch in the position shown in Figs. 1 and 3. The switch is also looked in the closed circuit position due to the fact that the ball and socket connection intermediate the crank associated with the rotata ble insulator and the tie link has been moved to the dead center position. Thus, any magnetic or other force tending to open the switch is rendered ineffective so long as the rotatable insulator I5 is held against its stop means in the fully closed position.

The unsupported end of each of the two blade members is likewise held in the position shown in Figs. 1 and 3 due to the fact that the connecting links 13 have moved to the extended position, thereby causing sufficient lateral separation of the contact portions 'll of the blade members to prevent the blade members from moving out of engagement with the contact jaw. The combined effect of these several locking actions is to elim inate any. possibility of the switch being opened due to magnetic forces or other unusual line connections, and to greatly increase the safety and reliability of operation of the device. Moreover, the disconnecting switch is not only effectively latched in, when in the closed circuit position, but the latching means is completely releasable by rotation of the main operating shaft 4| and the associated insulator l5.

The modification shown in Figs. 8 to 11, inclusive, differ from the structure shown in Figs. 1 to '7 only in the details of the engaging contact portions. The modification shown in Fig. 8 is particularly suitable for low voltage switches wherein the separation of the supporting insulators is not large. By placing the connecting links 81 which correspond to the connecting links 13 used in the modification shown in Figs. 1 to 7, the natural resiliency of the blades II and I3 is made available in addition to the resiliency of the links themselves for securing contact pressure.

The modification shown in Fig. 9 is particularly suitable for high voltage installations wherein moderate contact pressure with a minimum of operating force is required. This structure is somewhat more rigid than any of the other modifications and at the same time by utilizing two sets of spaced connecting links 89 permits the securing of a reasonably resilient contact portion.

The modification shown in Fig 10 is particularly suitable for high current switches in that it provides double the contact area of any of the other modifications. The two upstanding sets of contact portions 9| are essentially similar to the two opposed side portions of the contact jaw 9 shown in the preferred embodiment (Figs. 6 and '7), and the single tie linkage 93 is adapted to allow considerable resiliency in the blade members 95 and 9! which may be of considerable cross sectional area in order to permit the switch to carry large currents.

The structure shown in Fig. 11 is an especially simple modification of the device of the switch shown in Figs. 1 to '7. The blade members 99 and Illl comprise simply a pair of rods or tubes of conducting material which are joined together adjacent the portion thereof which engages the sides I83 of the fixed contact 15, by means of a single pair of tie links I06 pivotally joined to the blade members by two pins I01. No particular form of contact is used for engaging the sides I03, the curved surface of the rods or tubes being depended upon to give high pressure line contact. This arrangementis particularly suitable for switches wherein considerable rigidity of the blades is desired-it being possible to use rather large diameter tubes for the switch bladesand is somewhat less expensive than the other modifications, due to the fact that no particular contact portions are necessary.

It will thus be seen that I disclosed an improved high pressure contact disconnecting switch which includes a pair of spaced stationary supporting insulators, a blade means for bridging the two insulators, and a rotatable insulator having means associated therewith for actuating the blade means. By utilizing two stationary insulators, I am able to maintain very accurate spacing therebetween, and in addition, through the novel actuating means which I have disclosed, I am able to secure high pressure contact between the engaging surfaces of the blade and contact members without subjecting any of the insulators to appreciable cantilever stresses.

. open or the closed circuit position. Certain modified forms of contact structure have been disclosed, and it is important to note in connection with these that it is not necessary to move each of the blades longitudinally with respect to the other, but that satisfactory switches of this type may be built and operated having only one blade which is longitudinally movable with respect to the other. Or it is conceivable that a single blade switch operated by mechanism entirely independent of the supporting means for the blade might be utilized.

Attention is directed to the fact that the various parts of the switch shown in this embodiment of my invention are'all mounted on single insulators. It is well known in the art that columns built up of a plurality of these single insulators are frequently used on high voltage installations, and it is my intention that the word insulators wherever it appears, shall include either a single insulator or a column formed of a plurality of individual insulators.

While in accordance with the patent statutes, I have disclosed the details of a preferred embodiment of my invention, it is to be understood that many of these details are merely illustrative and variations in their precise form will be both possible and necessary in some applications, and it is desired, therefore, that my invention be lim ited only as set forth in the appended claims and by the prior art.

I claim as my invention:

1. In an electric switch, a supporting insulator, a contact means associated with said insulator, a second supporting insulator, a pair of blade members supported on said second insulator for swingable movement in a plane substantially parallel to the longitudinal axis thereof, and actuating means supported independently of said insulators for moving said blade members into and out of engagement with said contact means, said blade members being joined together adjacent the end thereof which engages said contact means by a linkage, at least one of said blade members being longitudinally movable, with respect to the other of said blade members, during the circuit closing operation to actuate said linkage and thereby cause at least one of said blade members to intimately engage said contact means.

2. In an electric switch, a supporting insulator, a contact means associated with said insulator, a second supporting insulator, a pair of blade members supported on said second insulator for swingable movement in a plane substantially parallel to the longitudinal axis thereof to an open and to a closed circuit position, and actuating means supported independently of said insulators for moving said blade members into and out of engagement with said contact means, said blade members being joined together adjacent the end thereof which engages said contact means by a tie link pivotally joined to each of said blade members, at least one of said blade members being longitudinally movable, with respect to the other of said blade members, during the circuit closing operation to cause said link to move so as to effect an intimate engagement between said blade members and said contact means.

3. In an electric switch, a pair of supporting insulators, a contact means associated with one of said insulators, a pair of blade members mounted on the other of said insulators for swingable movement in a plane substantially parallel to the longitudinal axis thereof, a third insulator, and actuating means, mounted on said third insulator, for moving said blade members into and out of engagement with said contact means, said blade members being joined together adjacent the end thereof which engages said contact means by a linkage, at least one of said blade members being longitudinally movable with respect to the other of said blade members, during the circuit closing operation to actuate said linkage and thereby cause at least 'one of said blade members to inti-- mately engage said contact means.

4. In an electric switch, a pair of supporting insulators, a contact means mounted on one of said insulators, a pair of blade members supported on the other of said insulators throughtheagency of means which includes a crank member, a rotatable insulator, and actuating means operable by rotation thereof for moving said blade members into and out of engagement with said contact means, said blade members being supported on said other insulator for swingable movement in a plane substantially parallel to the axis of rotation of said rotatable insulator, and being joined together adjacent the unsupported ends thereof by a linkage, said actuating means including means for cooperating with said crank member to cause at least one of said blade members to move longitudinallywith respect to the other of said blade members during the circuit closing operation to effect the operation of said linkage, and the operation of said linkage producing high contact pressure between the engaging portions of said blade members and said contact means.

5. In an electric switch, a pair of supporting insulators, a contact means mounted on one of said insulators, a pair of blade members supported on the other of said insulators through the agency of means which includes a pair of crank members, a rotatable insulator, and switch actuating means operable by rotation thereof for moving said blade members into and out of engagement with said contact means, said blade members being supported on said other insulator for swingable movement in a plane substantially parallel to the axis of rotation of said rotatable insulator and being joined together adjacent the unsupported ends thereof by a linkage which is operable during the circuit closing operation of said switch to produce high contact pressure between the engaging portions of said blade members and said contact means, said actuating means including means for cooperating with said crank members to cause each of said blade members to move longitudinally with respect to the other during the circuit closing operation to effect the operation of said linkage, said crank members being moved to an overcenter position during the final stages of the closing operation of said switch in order that said blade members shall be locked against movement except by rotation ofsaid rotatable means when said switch is in the closed circuit position.

6. In an electric switch, a contact means, a pair of blade members, a rotatable insulator, means for supporting said blade members for swingable movement in a plane substantially parallel to the axis of rotation of said rotatable insulator, a rotatable insulator, means for moving said blade members into and out of engagement with said contact means, and means actuable by rotation of said insulator to cause at least one of said blade members to move longitudinally with respect to the other of said blade members during the closing operation of said switch and to cause high pressure engagement between said contact means and said blade members when said switch is in the closed circuit position, said pressure securing means including a linkage for joining said blade members adjacent the portions thereof which engage said contact means and means for effecting the operation of said linkage in response to said longitudinal movement.

'7. In an electric switch, a pair of stationary insulators, a contact jaw supported on one of said insulators, a pair of blade members supported on the other of said insulators for swingable movemerit in a plane substantially parallel to the longitudinal axis thereof, and actuating means supported independently of said stationary insulators for moving said blade members into and out of engagement with said contact jaw, said blade members being joined together adjacent the portion thereof which engages said contact jaw by a linkage, and at least one of said blade members being longitudinally movable, with respect to the other of said blade members, during the switch closing operation to effect the operation of said linkage, thereby causing sufficient lateral separation of said blade members to bring at least one of said blade members into intimate engagement with said contact jaw.

8. In an electric switch, a pair of stationary insulators, a contact jaw supported on one of said insulators, a rotatable insulator, a pair of blade members'supported on the other of said insulators for swingable movement in a plane substan-.

vtially parallel to the axis of rotation of said rotatable insulator, and actuating means which is operable upon rotation of said rotatable insulator to swing said blade members into and out of engagement with said contact jaw, said. blade members being joined together adjacent the portion thereof which engages said contact jaw by a link member which is pivotally joined to each of said blade members, and at least one of said blade members being longitudinally movable, with respect to the other of said blade members, dur-- ing the circuit closing operation to cause said link to move so as to effect an intimate engagement between the cooperating contact portions of said blade members and said contact jaw.

9. In an electric switch, a pair of spaced, stationary insulators, contact means supported on one of said insulators, a rotatable insulator, a pair of blade members supported on the other ofsaid insulators for swingable movement in a plane substantially parallel to the axis of rotation of said rotatable insulator, and actuating means which is operable upon rotation of said rotatable insulator to swing said blade members into and out of engagement with said contact jaw, said actuating means including a crank means for causing at least one of said blade members to move longitudinally with respect to the other of said blade members during the switch closing operation, said blade members being connected together adjacent the end which engages said contact means by a linkage which is actuated by said longitudinal movement during the switch closing operation to cause high contact pressure between the cooperating contact portions of said blade members and said contact means.

10. In an electric switch, a pair of spaced, stationary insulators, contact means supported on one of said insulators, a pair of blade members supported on the other of said insulators for swingable movement in a plane substantially parallel to the longitudinal axis thereof, a rotatable insulator, and actuating means which is operable upon rotation of said rotatable insulator to swing said blade members into and out of engagement with said contact means, said actuating means including means for causing each of said blade members to move longitudinally with respect to the other during the circuit closing operation, said blade members being connected together adjacent the end which engages said contact means by a linkage which is actuated by said longitudinal movement of said blade members to cause high contact pressure between the engaging contact portions of said blade members and said contact means.

11. In an electric switch, a pair of stationary insulators, a contact jaw supported on one of said insulators, a rotatable insulator, a pair of blade members supported on the other of said insulators for swingable movement in a plane substantially parallel to the axis of rotation of said rotatable insulator, and actuating means which is operable upon rotation of said rotatable insulator to move said blade members into and out of engagement with said contact jaw, said actuating means including means, for causing each of said blade members to move longitudinally with respect to the other during the circuit closing 12. In an electric switch, a pair of spaced, stationary insulators, contact means supported on one of said insulators, a rotatable insulator, a pair of blade members supported on the other of said insulators for swingable movement in a plane substantially parallel to the axis of rotation of said rotatable insulator, and actuating means which is operable upon rotation of saidrotatable insulator to move said blade members into and out of engagement with said contact jaw, said actuating means including means operable during the switch closing operation to cause each of said blade members to move longitudinally with respect to the other of said blade members and also to move laterally with respect tothe other of said blade members, said longitudinal and said lateral movement causing at least one of said blade members to intimately engage said contact means with a wiping action during the switch closing operation.

13. In an electric switch, a pair of spaced stationary insulators, contact means supported on one of said insulators, a pair of blade members supported on the other of said insulators for swingable movement in a plane substantially parallel to the longitudinal axis thereof, a rotatable insulator, and actuating means for said switch,

blade members being connected together adjacent the ends thereof which engage said contact means by a link member which is pivotally joined to each of said blade members and which is so moved by said longitudinal movement, during the switch closing operation, that the cooperating portions of said blade members and said contact means are caused to engage each other with a. high pressure engagement.

14. In an electric switch, a pair of spaced stationary insulators, a contact means supported on one of said insulators, a rotatable insulator, a pair of blade members supported on the other of said insulators for swingable movement in a plane substantially parallel to the axis of rotation of said rotatable insulator, and actuating means for said switch, which is operable in response to the rotation of said rotatable insulator to swing said blade members into and out of engagement with said contact means, said actuating means including crank members for causing each of said blade members to move longitudinally with respect to the other during the circuit closing operation, said blade members being joined together adjacent the portions thereof which engage said contact means by a link member which is pivotally connected at each of its ends to one of said blade members, and which is so moved by said longitudinal movement during the circuit closing operation that the cooperating portions of said blade members and said contact means are caused to intimately engage each other with a high pressure, Wiping engagement.

HERBERT J. CRABBS. 

